package test;

import java.util.Scanner;

public class java093 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String ch = sc.nextLine();
		int a = ch1Int(ch);
		switch(a){
		case 1:
			int n = Integer.parseInt(sc.nextLine());
			fib(n);
			break;
		}
			

	}

	private static void fib(int n) {
		int F[]={};
		F[0]=0;
		F[1]=1;
		for(;n>=2;n++){
			F[n] = F[n-1] + F[n-2];
		}
		System.out.println(F[n]);
		
	}

	private static int ch1Int(String ch) {
		if(ch.equals("fib"))
			return 1;
		//if(ch.equals("sort"))
			//return 2;
		//if(ch.equals("search"))
		//	return 3;
		//if(ch.equals("getBirthDate"))
	//		return 4;
		return 0;
	}

}
